Rabbi Dr Fishel Szlajen, who sits on the Vatican’s Pontifical Academy for Life, has said scripture justifies abortion in certain rare cases.

In a largely pro-life article posted on Spanish-language site InfoBae, Dr Szlajen condemns abortion on demand, describing it as a crime that has been turned into a right. “‘The right to decide what to do with one’s own body’” manipulates and intentionally obscures the fact that we are dealing with “two distinct humans” he said.

However, he goes on to say that there is a case where scripture justifies killing the “conceptus” (the embryo in utero).

“In only one case does the Bible call for abortion: when the life of the conceptus inexorably threatens that of its mother,” he said. In such cases, the life of the mother takes priority.

Dr Szlajen justifies this position by citing the Jewish law of the “rodef”, which allows people in certain circumstances to kill someone who is endangering the lives of others.

Cases of anencephaly, irreversible degenerative pathologies and terminal disease where the “conceptus” will certainly die are examples of ‘tzorech gadol’ (grave necessity) where “abortion is permitted with severe restrictions”.

The same goes for a woman who has become pregnant through rape, and for whom continuing the pregnancy would result in “serious psychophysical danger”.

Speaking to the Catholic Herald, Dr Szlajen said that these exceptions were “peripheral” to the main thrust of his article, which “centrally deals with the absolute prohibition of abortion on demand from the Bible, and the refutation of the arguments that are used for decriminalising it”.

He stressed that “the zygote is an actual living human being (and not a potential one), and all maturational changes are phenotypic but not genotypic ones”. Only in “exceptional cases”, he said, when there is an “imminent threat of death from one human being to another”, does Jewish law permit abortion.

The principle of “rodef” has been widely debated in Jewish law, and has even been used to justify the assassination of Prime Minister Yitzhak Rabin in 1995. But Dr Szlajen said this case was a misapplication of the law: “It should be noted that under no circumstances can the law of rodef apply to Amir’s case. It was a murder by political motives.”

He said that his article was part of a “huge effort” to resist the attempts to introduce abortion on demand in Argentina.

Dr Szlajen is not the only member of the academy to back abortion in certain circumstances.

Before he was appointed, Professor Nigel Biggar said abortion was permissible before 18 weeks, adding: “It’s not clear that a human foetus is the same kind of thing as an adult.”

Another member of the academy, Rabbi Avraham Steinberg said the unborn child has “no human status” before 40 days. After 40 days, it has “a certain status of a human being, not full status”.

John Paul II taught that it was part of the Church’s unchanging tradition that abortion was always wrong, and that “No circumstance, no purpose, no law whatsoever can ever make licit an act which is intrinsically illicit, since it is contrary to the Law of God which is written in every human heart, knowable by reason itself, and proclaimed by the Church.”

This article has been updated with comments from Dr Szlajen. The headline has also been changed. It originally read “Member of Vatican pro-life academy says Bible justifies abortion in cases of rape and disability”.